Network policy can be used to prevent undesirable material from being retrieved by a computer. Such material can include malicious code that detrimentally modifies the behaviour of the retrieving computer, adult-oriented material that is unsuitable for viewing by a child that has access to the computer, and similar material.
In the past, proxies have been used to enforce policy by responding to requests with policy decisions, filtering content, and similar. However, placing a proxy between the requesting computers and the requested content can create a bottleneck, in that allowed requests may not be fulfilled quickly enough to meet demand. Further, administering proxies can be onerous, particularly in large organizations.